


In Mysterious Fathoms Below

by weytani



Series: Longshore Drift [2]
Category: Person of Interest (TV)
Genre: Alternate Universe - Mermaids, F/F, references to cannibalism
Language: English
Status: Completed
Published: 2019-07-13
Updated: 2019-07-13
Packaged: 2020-06-27 13:49:41
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 4,190
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19792180
Author URL: https://archiveofourown.org/users/weytani/pseuds/weytani
Summary: Things go south in a big way, and Shaw wakes up in an underground cave with nowhere to go. An old friend drops by to catch up.





	In Mysterious Fathoms Below

**Author's Note:**

> One-off sequel to "Mopin' on the Coastal Shelf", posted a few years back. I haven't read the book that fic was based on since then, so this is more of a loose AU based on the premise.
> 
> Any sharp-eyed people may notice I posted this a few weeks ago, and took it down pretty quick. Yeah, knee-jerk reaction to some negative feedback, but after looking this over again today I don't feel too bad about it. @ that person, sorry it wasn't for you, I guess? Point taken!
> 
> Title from The Little Mermaid soundtrack (naturally). Warning for some talk of eating people and sea monsters that resemble people. Also for some borderline(?) sexual content... they're alone in a cave...

Shaw remembers lying face-up on the deck, watching clouds move in lazy wisps across the otherwise blue sky. Two days from shore. Fourteen dead and six bruised and battered survivors with one man’s rations between them.

Shaw remembers, in vivid, choppy frames like a bright light flickering on every few seconds as the pictures stick: Joss standing at the helm with Martine, arguing over how best to separate out their food. The sails barely catching on the summer breeze, still patchwork, one sewn with a square of fabric cut from Shaw’s own t-shirt a day earlier.

The sound of boards creaking and the ocean rocking their ship in gentle hands.

And then, all at once, a horn in the distance. Shaw remembers; she blinks and the sun is peeled back from the sky by dark clouds, where a minute ago there had been none. The deck creaks again, this time in agitation, and the world tips out from under her.

Water below and then around and above. It’s quiet underneath. Shaw reaches for the surface and kicks blindly for momentum, but fingers snake around her ankle, the back of her shirt, and an arm like a steel bar locks around her waist to pull her deeper. Not enough air, not enough time to think—

And then she wakes up.

It’s not until Shaw rolls over and hacks up a mouthful of seawater that she realises she’s back on dry land, damp clothes almost glued to her skin in the cold air. Her palms smack loudly against the flat rock she’s hunched over, and the sound echoes in the gloomy darkness. A cave, or something like it. There’s water nearby, she can hear the waves like a rough exhale to her right.

Shaw’s good, but she’s not good enough to win a fight underwater and swim to shore while unconscious. Someone else must have pulled her out of the water.

When her eyes start to adjust a little better, she does a sweep of the cave. The ceiling is low, but she can just about stand up and stretch her legs out before her head brushes the stalactites forming in jagged peaks across its surface.

The rock she woke up on connects to a pathway of others just like it, all sleek and flat and packed together into a natural shore-like platform, ending in a ridge where Shaw leans out and stares at her own reflection in the black water below, about five inches down. On all sides, the walls slope in and up, a perfect circle with no way out.

She’s been spared from drowning to be left for dead in this shit-hole. What a joke.

There must be a tunnel underwater, leading back out to the wider ocean, but there’s no telling how far in-land this cave has formed. The beasts had brought her here, that much is obvious; maybe they’d filled up on the rest of her crew, figured they could store the fresh produce for a while and pick her bones clean later when the sun goes down.

It’s not like she blames them— Shaw’s no moral authority by any stretch of the imagination. Not even close.

Two days ago, when they were throwing the bodies overboard in the aftermath of that last fight, Shaw had paused, fingers splayed across the limp tail of one the corpses. She’d pondered on it, briefly, and reached for her knife when the others had their backs turned.

The scaled flesh wasn’t easy to penetrate, but eventually she managed to gouge out a piece. It was pink on the inside, like any other fish they’d caught back home and seared over their campfires on wooden pikes. Would it taste the same? That’s what she’d thought about.

“Don’t.”

Joss had turned around.

Shaw held the meat up in her palm, gaze steady. “They’ve done it. They’ll do it again. We kill them, we dump their bodies, and we eat like starving orphans. And we lose every time.”

“Not today,” Joss had said. She smacked the up-turned hand away, and Shaw let it drop passively, watching the gristle and blood seep out across the boards. “We’re not the same as them.”

So, turns out it’s morally wrong to eat the mermaids. Shaw doesn’t get it, not really, but she knows enough to take her cues from Carter, who’s the closest thing she has to a role model these days, if she were actually looking for one.

It makes her wonder, though, how the others had fared when the ship went over. Had it turned a full one-eighty and sunk to the ocean floor with half their group still caught below deck? Martine can bite it, but Joss is too good for that. And Shaw kind of likes Harper and the others, most days. Maybe they’re all dead anyway.

She isn’t dead yet.

Her odds suck though; she’ll have to swim down and try her luck in the tunnel, find an exit before she runs out of air or meets her dinner date on the way through. Or wait and try to catch one of those things off-guard, pin them down for information and an exit strategy.

Weapon first. Shaw casts her eyes around the cave again. No loose stones in sight, but then she looks up, and some of the stalactites are sharper at the tip, enough to break skin with enough pressure applied. Shaw reaches up and wraps both hands around the best of them, trying to break the column away from the ceiling without shattering it. Her body is still fatigued from the stint underwater, so it takes some time, but eventually she manages to snap off an edge the length of her middle finger.

She grunts and stumbles back a bit when it happens, and suddenly there’s a wet sound, like a gurgle, from the pool of water behind her. In an instant, Shaw turns, holding the rock up with its point jutting out of her palm, as if she were holding a knife.

There’s a head poking out of the water, submerged just under the nose. Shaw can make out the dark curls of hair and distinctive facial features of Root, even in the dark.

“You again, huh,” Shaw mutters, tense and ready for any sudden movements. But Root just looks at her for a moment, a long stare with un-blinking eyes that glow faintly and reflect in the water between them.

Shaw holds that calculated gaze, doesn’t flinch when she sinks out of sight and appears again seconds later by the water’s edge to her left. Thin, pale arms reach out and settle on the stone lip of the platform, and Root seems to hoist herself up effortlessly until her shoulders are out of the water. She tilts her head at Shaw, whose eyes follow her every move warily, and rests her chin on one forearm.

“Is that for me?” Shaw narrows her eyes at the amusement in Root’s voice. Not the first time she’s been underestimated – Shaw’s not that tall, not broad like some of the women back home – but it’s usually not by an enemy she’s already stabbed once.

“All depends on what you do next,” Shaw says. “Not like I don’t have a marker lined up from last time.”

Last time…

_I kept your gift_ , that’s what she’d said. Flirtatious, like the knife wound on her shoulder was a thoughtful offering from an old lover, and not a near-stranger who wanted her dead. Wants her dead, presently.

From the expression on Root’s face, they’re both reliving that conversation. She’s smiling now, and looking up at Shaw through long eyelashes as she leans back from the rock. Just far enough to run a hand across her collarbone in Shaw’s line of sight, across bare skin, still pink— and Shaw was right before, the escalated healing process has left a noticeable scar.

“This,” Root says, tracing it delicately with a finger. “This took me by surprise. When I pulled the blade out… it was a little overwhelming, you know. Bloody. The sharks took an interest.”

Root’s sharp teeth glint in the darkness when she bares them, smile turning feral, and Shaw’s face gives nothing away, but she feels a coil of something sick and excited winding its way up her throat.

“Who taught you English?” she asks, ignoring whatever _that_ was.

“I’m a good listener,” is all Root says for a moment. She drums her fingers against her chest thoughtfully, but Shaw keeps her eyes pinned above the neck. “Oceans connect, and humans never really learn. But we do—well, the best of us anyway. And I learn a little faster than most.”

That patronising little smile on her face makes Shaw want to lash out, but the timing needs to be on her side. There’s no telling how many hours have passed, how long it’s been since she last ate; if she doesn’t play this right, she’ll end up flat on her back like the last time they met. And those gangly arms are stronger than they look.

“Lure. That’s the word you use, isn’t it? When you can’t quite hold it together, and the big, bad mermaid tries to liquify your brain,” Root continues, pressed to the end of the stone and sweeping her hair back over one shoulder. “But in reality, you’re just experiencing a physiological response to something baser. And even when you’re not really susceptible…”

Shaw grips the make-shift weapon tighter when Root’s back hunches and she lifts her upper body up onto land, the subtle green-grey crisscross of scales at her waist becoming visible as she manoeuvres into a sitting position.

She’s beautiful. Of course she is, they all are, which is the point. Those big, innocent-looking eyes, the slender neck, and if Shaw spends more than five seconds leering at her breasts it’s out of pure consternation and nothing else.

Root basks in the attention, droplets of water making trails down her shoulders, her sternum, pattering to the stones with a soft plink. Shaw catches herself following one and snaps her eyes back up, but doesn’t retreat any further; they’re still not within reach of each other, and she wants Root as far from the pool as she can get her for a fair fight.

“You’re still a victim to your urges.”

“You brought me here,” Shaw says immediately, like Root hasn’t spoken a word, and she takes pleasure in the agitated twitch of Root’s eyes. “Could’ve pulled me down to the ocean floor, but no. You dragged me all the way up here so I could listen to you monologue. I’d rather drown, if it’s all the same.”

“Not a very nice way to say ‘thank you’.” Root frowns theatrically, drawing a line down one cheek with her index finger. “You could hurt my feelings, talking like that after I went to so much trouble.”

No wonder we’re sent out to kill these things, Shaw thinks with a grimace, if they’re all this fucking irritating.

“Come over here and I’ll show you some gratitude.”

Root’s eyebrows perk up, and she glances at the rock in Shaw’s hand, following through into a long, drawn out rake across the rest of her body with curious eyes. “I wonder…”

Her voice comes out with an almost breathy quality, and she’s still looking Shaw up and down like she’s sizing her up. To what end, Shaw can’t quite discern. Maybe it’s time for dinner.

Root turns to face her fully, waist rotating until her tail breaks the waterline behind her, forked fins wavering in the open air. She draws herself closer to Shaw with fingers slotted in thin cracks between the stones, inch by inch, but slowly with intent. And just out of reach, rears up like a viper with the smile to match.

“Here I am, Shaw,” Root says, and they’re about the same height like this. Her eyes are bright and predatory as she meets Shaw’s level stare. “What happens now?”

Immediately, Shaw goes for the throat. Jerking forward, knuckles tight around the limestone, before the words are fully out of her mouth. Root’s fingers latch around her wrist, but Shaw’s other hand takes up a fistful of that long, damp hair and yanks it down to pull her off-balance.

Root hisses, guttural with the pain of it, and reaches up instinctively to ease the sting. From one second to the next, Shaw’s released her hair and dropped the sharpened rock into her open palm, straightening her elbow out to drive it into the unprotected back of Root’s neck.

The limestone hits on target, visibly indents the pale skin between Root’s shoulders, and shatters in the palm of Shaw’s hands like porcelain glass. Crumbling into pieces that roll down Root’s back, and leaving behind a red bruise that’s already fading as Shaw stares at it.

Root’s fingers tighten around her wrist and drag her down roughly, with enough force to pull Shaw’s arm out of the socket is she tries to break free. Against her will, she ends up on her knees, teeth gritted as she retracts her free hand and tries to punch Root in the side of the head, to no apparent effect.

She can’t see Root’s expression through the tangle of hair, but there’s a manic energy in the way her tail slides back and forth along the stone floor. Shaw foresees teeth and nails and a geyser of blood in her near future, but at least she’s probably wiped that smug look off Root’s face.

“Hope you choke on my small intestine, bitch,” Shaw snaps, before Root jumps her hard enough to throw them both down and knock the air out of her lungs.

This time, instead of the floor, Shaw’s back hits the wall of the cave, ridges scraping at her shoulders and pulling her shirt up enough bare her waist to the cool breeze around them. Shaw grits her teeth as Root’s long form settles over her, between her splayed legs, feeling scales slide across the bare skin of her stomach. The stones are damp beneath her, and her clothes are still sodden and crumpled, but Root is generating the steady heat of coals piled in a firepit, and it’s not wholly uncomfortable.

She’s got a tight hold of Shaw’s wrists, one in each hand, and she pushes them back against the wall just above her shoulders.

“You think I want to eat you?” Root asks, sounding amused. She tilts her head back and to the side, sweeping a curtain of hair over one shoulder to bare the excited grin on her face. Shaw hasn’t enraged her; if anything, Root looks like she enjoyed the rough treatment. “What a waste that would be.”

“What am I, a toy for you to play with? No more action when you’ve finished with our hunting ships, so you keep a few spares around for the off-season?”

Shaw tries to dig her heels into the floor and skids a few times before she has any progress. She leans into the pressure keeping her arms held down and lurches up, trying to buck Root’s body off. Unsuccessfully—Root’s all tucked up between her legs, stomach to stomach, and she seems in no rush to change that.

Instead, she leans closer, snickering at the failed attempt to move her, and at the grimace on Shaw’s face when she lands hard on her ass a moment later. Root follows her down to the ground, closer than ever now that Shaw’s got no more room to manoeuvre.

“No, sweetie.” Shaw’s eyes narrow, jaw twitching at the pet name. “No, you’re a special case.”

“And what does that mean for me?”

Root declines to answer this time, instead choosing to pin Shaw with the full effect of that luminescent stare at close range. It’s unusual to Shaw, the way Root’s eyes don’t ever really close, just narrow in consideration as she peers from Shaw’s face to where her shirt is still gathered halfway down her torso. One of Root’s hands unfolds from around her wrist, releasing it from the wall as she drops her palm to the floor beside them for better leverage.

Shaw glances up at the stone ceiling, trying to laser-focus a rockslide into effect with no success. Being powerless makes her frustrated, tense with reserves of energy she can’t use with one hand pinned to the wall and a she-creature keeping her grounded. The warmth Root is emitting though, that’s causing its own set of problems.

She shifts herself up just a little, scaled hips dragging over the seam of Shaw’s trousers, and Shaw can’t help the air that slips out between gritted teeth. Worse still is the way her thigh muscles tighten around Root’s waist involuntarily.

_Oh, fuck that_.

Immediately, Root’s whole body seems to pause. She looks down at Shaw’s face from directly above, pupils darting like she’s trying to drink in any minute reaction from what just occurred. Shaw’s glare is a fortress of reinforced steel, and while there’s no road to victory when inciting a staring contest with an entity who doesn’t blink, Shaw takes a real shot at it.

Water drips from the ceiling in long intervals, echoing in the dark cavern.

“That’s interesting,” Root says quietly.

She takes her free hand away from the floor, long fingers unfurling into an open palm that settles on Shaw’s bare stomach. The intimacy of this new contact makes Shaw’s muscles clench again, and Root presses into it, fingertips digging in and pulling at the skin.

It’s a rough touch, calculated to bring out a response, and Shaw won’t let her have one. This is a game she can win with both hands tied, and she’s still got one in commission.

“Is that the best you can do?” she whispers heatedly.

Root squeezes harder, jagged teeth peeking out of her mouth. “Let’s find out.”

With an angelic smile on her face, she eases her hand up Shaw’s stomach until it reaches the bundled fabric of her shirt. Shaw tilts her head back against the wall, feigning disinterest even as Root’s fingers creep underneath, inching towards the bindings over her chest.

“All these layers, and none of them very effective.”

Warmth envelopes the swell of Shaw’s breast, pressing down against her nipple. The feeling of Root’s palm taking hold of her so confidently, pulling, pushing, rotating in practiced motions, is starting to get to her. Even through the bandages, it makes her skin burn with sensitivity.

Quickly enough, Root stops playing nice and squeezes tighter, catching Shaw’s nipple between her thumb and index finger. Her eyes are locked on Shaw’s face, widening in satisfaction when Shaw’s mouth opens almost imperceptibly.

“Is this how they touch you, out there on your island? On your ships?” Root punctuates the question with a sharp flick of her index finger, before falling back into her earlier ministrations.

Shaw wants to leave her hanging again, but the urge to draw back some power takes priority.

“Not since puberty, but points for enthusiasm,” she says, aiming for deadpan and firing just a little short of breathy. Root’s managed to unravel some of the bindings now, and her nails catch as she speeds up her strokes. “Don’t… don’t expect me to fertilize your eggs or anything freaky like that. I hate kids.”

“You’re ruining the mood, Shaw,” Root murmurs playfully. “Should I stop?”

“I didn’t say that.”

They don’t talk for a while after that, and Shaw doesn’t feel any kind of shame in letting this go on. Root’s hand feels good, and the way she rolls her hips against Shaw’s in a slow, teasing rhythm feels pretty great, too. Even with the cold, rigid stones at her back, and one arm still clasped against the cave wall above her head, she doesn’t want to move an inch until Root’s face gets a little too close to hers.

Shaw turns her head, and Root noses at her cheek, grinning in that innocent but altogether manic way.

“Can I kiss you?” Breathed eagerly against the shell of her ear. And then, “Please.”

“Not with those shark-teeth, you won’t.” Shaw likes to play on the wilder side when it comes to foreplay, she can own up to that, but she draws the line at sticking her tongue into a human bear trap.

“Fine,” Root says, before opening her mouth and scraping the tips of her teeth against the cut of Shaw’s jawbone, light as a feather but still razor-sharp. Shaw tilts her head minutely, catching herself before she can all but open up to the weapon at her throat. Root’s fingers are still rubbing at her breast beneath her shirt, distracting and warm and throwing Shaw’s brain off-track every time she pinches right _there_.

When something wet runs a slippery trail back up to her ear, Shaw finally lifts her free hand and slams it around Root’s neck in a vice-like grip, forcing her head back a few inches.

Root makes a surprised little hiss at the sudden show of strength, but doesn’t retaliate or even stop pawing at her as Shaw squeezes her fingers experimentally, flexing them in a silent threat.

“Did I scare you?” Root asks, when Shaw eases the pressure briefly.

“I don’t get scared.”

Not like the others. That’s why she topped the ranks as a recruit, made no friends, and held no real interest in forming bonds with people who would soon die before her eyes. That’s why she’s here now, in the dark, tangled up with an enemy who looks ready to eat her or fuck her at any given moment.

Root considers her for a moment through half-lidded eyes, and then raises her chin, leaning into the hand around her neck. “Harder.”

Shaw sneers and straightens her arm, locking her fingers in tight enough to throttle a human being. Root just seems to enjoy it if anything, and Shaw thinks, if she can do this hard enough, then maybe the bruises will last like the scar in her shoulder.

Root presses herself down into the palm of Shaw’s hand, and rocks her hips, trying to keep her own rhythm going against Shaw’s chest and faltering, but it still feels good. It all feels amazing.

A loud splash echoes around the chamber, jarring them both out of whatever trance has been building. Long, skinny arms slap against the stone platform at the edge of the pool, and a dark figure rises out of the water.

“ _Root._ ”

Another mermaid, one looking enraged and battered in the face, with her hair slicked back close to her scalp. She stares at Root, eyes blazing, and then down to Shaw’s form sprawled on the cave floor, with Root’s hand still tucked under her shirt.

Something rapid and brimming with disgust spits from her lips, and Shaw can’t understand a word of it but Root seems content to fill her in, even as the other mermaid keeps screaming at them.

“She says I’m debasing myself, and that your organs would be better served to the worms on the ocean floor.”

“Spare me the translation.”

“Sorry,” Root scrunches her nose up as Shaw lets go of her neck, and finally takes her own hands away so Shaw can push herself up against the wall. “You have a right to know.”

Their company doesn’t seem to like being ignored, as her screaming veers into a shrill wailing that pricks at Shaw’s eardrums. The hunch of her shoulders looks familiar, close to the gesture Root had made earlier, before she jumped Shaw from across the room.

Shaw had been on her back foot against Root, sure, but she’ll try her luck again if she needs to. This one is shorter at least, and clearly blind with rage.

“Looks like we’re out of time again,” Root says, taking hold of a natural ridge in the wall to rise up beside her. The tone of Root’s voice is light and unaffected, like this new arrival is of no concern to either of them. “Hold your breath and swim down, there’s a tunnel out to the sea.”

Shaw glances over, and Root smiles with her teeth on display, looking every bit the carnivorous monster that she is. And for a moment, Shaw lets herself smirk back.

“Try not to suffocate.”

“Next time we meet, I’m aiming for the heart.”

Root’s eyes glow faintly, her pupils tinting red as Shaw turns to make a run for the pool. She dives, catching an image of Root slamming her ally’s head into the stone floor with a sickening crack, and then the water swallows her down.

-

When Shaw breaks the surface, lungs on fire and heart pounding, but still somehow alive, there’s a beach not a mile out from where she’s treading water.

Breathing in heavy, painful gasps, she puts a hand up over her eyes to block out the sun.

And there, sprawled out on the sand like they’ve just dragged themselves out of the ocean, are four bodies that might still be alive.

Shaw doesn’t believe in miracles, but this one feels like a freebie.


End file.
